<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
<title>pugixml 1.0</title>
<link rel="stylesheet" href="pugixml.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.75.2">
<link rel="home" href="quickstart.html" title="pugixml 1.0">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<div class="article">
<div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="quickstart.main"></a><a class="link" href="quickstart.html#quickstart.main" title="pugixml 1.0 quick start guide"> pugixml 1.0 quick start guide</a>
</h2></div></div></div>
<div class="toc"><dl>
<dt><span class="section"><a href="quickstart.html#quickstart.main.introduction"> Introduction</a></span></dt>
<dt><span class="section"><a href="quickstart.html#quickstart.main.install"> Installation</a></span></dt>
<dt><span class="section"><a href="quickstart.html#quickstart.main.dom"> Document object model</a></span></dt>
<dt><span class="section"><a href="quickstart.html#quickstart.main.loading"> Loading document</a></span></dt>
<dt><span class="section"><a href="quickstart.html#quickstart.main.access"> Accessing document data</a></span></dt>
<dt><span class="section"><a href="quickstart.html#quickstart.main.modify"> Modifying document data</a></span></dt>
<dt><span class="section"><a href="quickstart.html#quickstart.main.saving"> Saving document</a></span></dt>
<dt><span class="section"><a href="quickstart.html#quickstart.main.feedback"> Feedback</a></span></dt>
<dt><span class="section"><a href="quickstart.html#quickstart.main.license"> License</a></span></dt>
</dl></div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="quickstart.main.introduction"></a><a class="link" href="quickstart.html#quickstart.main.introduction" title="Introduction"> Introduction</a>
</h3></div></div></div>
<p>
        <a href="http://pugixml.org/" target="_top">pugixml</a> is a light-weight C++ XML
        processing library. It consists of a DOM-like interface with rich traversal/modification
        capabilities, an extremely fast XML parser which constructs the DOM tree
        from an XML file/buffer, and an XPath 1.0 implementation for complex data-driven
        tree queries. Full Unicode support is also available, with Unicode interface
        variants and conversions between different Unicode encodings (which happen
        automatically during parsing/saving). The library is extremely portable and
        easy to integrate and use. pugixml is developed and maintained since 2006
        and has many users. All code is distributed under the <a class="link" href="quickstart.html#quickstart.main.license" title="License">MIT
        license</a>, making it completely free to use in both open-source and
        proprietary applications.
      </p>
<p>
        pugixml enables very fast, convenient and memory-efficient XML document processing.
        However, since pugixml has a DOM parser, it can't process XML documents that
        do not fit in memory; also the parser is a non-validating one, so if you
        need DTD/Schema validation, the library is not for you.
      </p>
<p>
        This is the quick start guide for pugixml, which purpose is to enable you
        to start using the library quickly. Many important library features are either
        not described at all or only mentioned briefly; for more complete information
        you <a href="manual.html" target="_top">should read the complete manual</a>.
      </p>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
          No documentation is perfect, neither is this one. If you encounter a description
          that is unclear, please file an issue as described in <a class="xref" href="quickstart.html#quickstart.main.feedback" title="Feedback"> Feedback</a>. Also if
          you can spare the time for a full proof-reading, including spelling and
          grammar, that would be great! Please <a class="link" href="quickstart.html#email">send me an e-mail</a>;
          as a token of appreciation, your name will be included into the corresponding
          section of the manual.
        </p></td></tr>
</table></div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="quickstart.main.install"></a><a class="link" href="quickstart.html#quickstart.main.install" title="Installation"> Installation</a>
</h3></div></div></div>
<p>
        pugixml is distributed in source form. You can download a source distribution
        via one of the following links:
      </p>
<pre class="programlisting"><a href="http://pugixml.googlecode.com/files/pugixml-1.0.zip" target="_top">http://pugixml.googlecode.com/files/pugixml-1.0.zip</a>
<a href="http://pugixml.googlecode.com/files/pugixml-1.0.tar.gz" target="_top">http://pugixml.googlecode.com/files/pugixml-1.0.tar.gz</a>
</pre>
<p>
        The distribution contains library source, documentation (the guide you're
        reading now and the manual) and some code examples. After downloading the
        distribution, install pugixml by extracting all files from the compressed
        archive. The files have different line endings depending on the archive format
        - <code class="filename">.zip</code> archive has Windows line endings, <code class="filename">.tar.gz</code> archive has Unix line endings.
        Otherwise the files in both archives are identical.
      </p>
<p>
        The complete pugixml source consists of three files - one source file, <code class="filename">pugixml.cpp</code>,
        and two header files, <code class="filename">pugixml.hpp</code> and <code class="filename">pugiconfig.hpp</code>. <code class="filename">pugixml.hpp</code> is the primary
        header which you need to include in order to use pugixml classes/functions.
        The rest of this guide assumes that <code class="filename">pugixml.hpp</code> is either in the current directory
        or in one of include directories of your projects, so that <code class="computeroutput"><span class="preprocessor">#include</span> <span class="string">"pugixml.hpp"</span></code>
        can find the header; however you can also use relative path (i.e. <code class="computeroutput"><span class="preprocessor">#include</span> <span class="string">"../libs/pugixml/src/pugixml.hpp"</span></code>)
        or include directory-relative path (i.e. <code class="computeroutput"><span class="preprocessor">#include</span>
        <span class="special">&lt;</span><span class="identifier">xml</span><span class="special">/</span><span class="identifier">thirdparty</span><span class="special">/</span><span class="identifier">pugixml</span><span class="special">/</span><span class="identifier">src</span><span class="special">/</span><span class="identifier">pugixml</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>).
      </p>
<p>
        The easiest way to build pugixml is to compile the source file, <code class="filename">pugixml.cpp</code>,
        along with the existing library/executable. This process depends on the method
        of building your application; for example, if you're using Microsoft Visual
        Studio<sup>[<a name="trademarks" href="#ftn.trademarks" class="footnote">1</a>]</sup>,
        Apple Xcode, Code::Blocks or any other IDE, just add <code class="filename">pugixml.cpp</code> to one of
        your projects. There are other building methods available, including building
        pugixml as a standalone static/shared library; <a href="manual/install.html#manual.install.building" target="_top">read
        the manual</a> for further information.
      </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="quickstart.main.dom"></a><a class="link" href="quickstart.html#quickstart.main.dom" title="Document object model"> Document object model</a>
</h3></div></div></div>
<p>
        pugixml stores XML data in DOM-like way: the entire XML document (both document
        structure and element data) is stored in memory as a tree. The tree can be
        loaded from character stream (file, string, C++ I/O stream), then traversed
        via special API or XPath expressions. The whole tree is mutable: both node
        structure and node/attribute data can be changed at any time. Finally, the
        result of document transformations can be saved to a character stream (file,
        C++ I/O stream or custom transport).
      </p>
<p>
        The root of the tree is the document itself, which corresponds to C++ type
        <code class="computeroutput"><span class="identifier">xml_document</span></code>. Document has
        one or more child nodes, which correspond to C++ type <code class="computeroutput"><span class="identifier">xml_node</span></code>.
        Nodes have different types; depending on a type, a node can have a collection
        of child nodes, a collection of attributes, which correspond to C++ type
        <code class="computeroutput"><span class="identifier">xml_attribute</span></code>, and some additional
        data (i.e. name).
      </p>
<p>
        The most common node types are:
      </p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
            Document node (<code class="computeroutput"><span class="identifier">node_document</span></code>)
            - this is the root of the tree, which consists of several child nodes.
            This node corresponds to <code class="computeroutput"><span class="identifier">xml_document</span></code>
            class; note that <code class="computeroutput"><span class="identifier">xml_document</span></code>
            is a sub-class of <code class="computeroutput"><span class="identifier">xml_node</span></code>,
            so the entire node interface is also available.
          </li>
<li class="listitem">
            Element/tag node (<code class="computeroutput"><span class="identifier">node_element</span></code>)
            - this is the most common type of node, which represents XML elements.
            Element nodes have a name, a collection of attributes and a collection
            of child nodes (both of which may be empty). The attribute is a simple
            name/value pair.
          </li>
<li class="listitem">
            Plain character data nodes (<code class="computeroutput"><span class="identifier">node_pcdata</span></code>)
            represent plain text in XML. PCDATA nodes have a value, but do not have
            name or children/attributes. Note that plain character data is not a
            part of the element node but instead has its own node; for example, an
            element node can have several child PCDATA nodes.
          </li>
</ul></div>
<p>
        Despite the fact that there are several node types, there are only three
        C++ types representing the tree (<code class="computeroutput"><span class="identifier">xml_document</span></code>,
        <code class="computeroutput"><span class="identifier">xml_node</span></code>, <code class="computeroutput"><span class="identifier">xml_attribute</span></code>);
        some operations on <code class="computeroutput"><span class="identifier">xml_node</span></code>
        are only valid for certain node types. They are described below.
      </p>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
          All pugixml classes and functions are located in <code class="computeroutput"><span class="identifier">pugi</span></code>
          namespace; you have to either use explicit name qualification (i.e. <code class="computeroutput"><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span></code>), or to gain access to relevant
          symbols via <code class="computeroutput"><span class="keyword">using</span></code> directive
          (i.e. <code class="computeroutput"><span class="keyword">using</span> <span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span><span class="special">;</span></code> or <code class="computeroutput"><span class="keyword">using</span>
          <span class="keyword">namespace</span> <span class="identifier">pugi</span><span class="special">;</span></code>).
        </p></td></tr>
</table></div>
<p>
        <code class="computeroutput"><span class="identifier">xml_document</span></code> is the owner
        of the entire document structure; destroying the document destroys the whole
        tree. The interface of <code class="computeroutput"><span class="identifier">xml_document</span></code>
        consists of loading functions, saving functions and the entire interface
        of <code class="computeroutput"><span class="identifier">xml_node</span></code>, which allows
        for document inspection and/or modification. Note that while <code class="computeroutput"><span class="identifier">xml_document</span></code> is a sub-class of <code class="computeroutput"><span class="identifier">xml_node</span></code>, <code class="computeroutput"><span class="identifier">xml_node</span></code>
        is not a polymorphic type; the inheritance is present only to simplify usage.
      </p>
<p>
        <code class="computeroutput"><span class="identifier">xml_node</span></code> is the handle to
        document node; it can point to any node in the document, including document
        itself. There is a common interface for nodes of all types. Note that <code class="computeroutput"><span class="identifier">xml_node</span></code> is only a handle to the actual
        node, not the node itself - you can have several <code class="computeroutput"><span class="identifier">xml_node</span></code>
        handles pointing to the same underlying object. Destroying <code class="computeroutput"><span class="identifier">xml_node</span></code> handle does not destroy the node
        and does not remove it from the tree.
      </p>
<p>
        There is a special value of <code class="computeroutput"><span class="identifier">xml_node</span></code>
        type, known as null node or empty node. It does not correspond to any node
        in any document, and thus resembles null pointer. However, all operations
        are defined on empty nodes; generally the operations don't do anything and
        return empty nodes/attributes or empty strings as their result. This is useful
        for chaining calls; i.e. you can get the grandparent of a node like so:
        <code class="computeroutput"><span class="identifier">node</span><span class="special">.</span><span class="identifier">parent</span><span class="special">().</span><span class="identifier">parent</span><span class="special">()</span></code>;
        if a node is a null node or it does not have a parent, the first <code class="computeroutput"><span class="identifier">parent</span><span class="special">()</span></code>
        call returns null node; the second <code class="computeroutput"><span class="identifier">parent</span><span class="special">()</span></code> call then also returns null node, so you
        don't have to check for errors twice. You can test if a handle is null via
        implicit boolean cast: <code class="computeroutput"><span class="keyword">if</span> <span class="special">(</span><span class="identifier">node</span><span class="special">)</span> <span class="special">{</span> <span class="special">...</span> <span class="special">}</span></code>
        or <code class="computeroutput"><span class="keyword">if</span> <span class="special">(!</span><span class="identifier">node</span><span class="special">)</span> <span class="special">{</span> <span class="special">...</span> <span class="special">}</span></code>.
      </p>
<p>
        <code class="computeroutput"><span class="identifier">xml_attribute</span></code> is the handle
        to an XML attribute; it has the same semantics as <code class="computeroutput"><span class="identifier">xml_node</span></code>,
        i.e. there can be several <code class="computeroutput"><span class="identifier">xml_attribute</span></code>
        handles pointing to the same underlying object and there is a special null
        attribute value, which propagates to function results.
      </p>
<p>
        There are two choices of interface and internal representation when configuring
        pugixml: you can either choose the UTF-8 (also called char) interface or
        UTF-16/32 (also called wchar_t) one. The choice is controlled via <code class="computeroutput"><span class="identifier">PUGIXML_WCHAR_MODE</span></code> define; you can set
        it via <code class="filename">pugiconfig.hpp</code> or via preprocessor options. All tree functions that
        work with strings work with either C-style null terminated strings or STL
        strings of the selected character type. <a href="manual/dom.html#manual.dom.unicode" target="_top">Read
        the manual</a> for additional information on Unicode interface.
      </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="quickstart.main.loading"></a><a class="link" href="quickstart.html#quickstart.main.loading" title="Loading document"> Loading document</a>
</h3></div></div></div>
<p>
        pugixml provides several functions for loading XML data from various places
        - files, C++ iostreams, memory buffers. All functions use an extremely fast
        non-validating parser. This parser is not fully W3C conformant - it can load
        any valid XML document, but does not perform some well-formedness checks.
        While considerable effort is made to reject invalid XML documents, some validation
        is not performed because of performance reasons. XML data is always converted
        to internal character format before parsing. pugixml supports all popular
        Unicode encodings (UTF-8, UTF-16 (big and little endian), UTF-32 (big and
        little endian); UCS-2 is naturally supported since it's a strict subset of
        UTF-16) and handles all encoding conversions automatically.
      </p>
<p>
        The most common source of XML data is files; pugixml provides a separate
        function for loading XML document from file. This function accepts file path
        as its first argument, and also two optional arguments, which specify parsing
        options and input data encoding, which are described in the manual.
      </p>
<p>
        This is an example of loading XML document from file (<a href="samples/load_file.cpp" target="_top">samples/load_file.cpp</a>):
      </p>
<p>
        
</p>
<pre class="programlisting"><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_document</span> <span class="identifier">doc</span><span class="special">;</span>

<span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_parse_result</span> <span class="identifier">result</span> <span class="special">=</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">load_file</span><span class="special">(</span><span class="string">"tree.xml"</span><span class="special">);</span>

<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"Load result: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">result</span><span class="special">.</span><span class="identifier">description</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="string">", mesh name: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">child</span><span class="special">(</span><span class="string">"mesh"</span><span class="special">).</span><span class="identifier">attribute</span><span class="special">(</span><span class="string">"name"</span><span class="special">).</span><span class="identifier">value</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
</pre>
<p>
      </p>
<p>
        <code class="computeroutput"><span class="identifier">load_file</span></code>, as well as other
        loading functions, destroys the existing document tree and then tries to
        load the new tree from the specified file. The result of the operation is
        returned in an <code class="computeroutput"><span class="identifier">xml_parse_result</span></code>
        object; this object contains the operation status, and the related information
        (i.e. last successfully parsed position in the input file, if parsing fails).
      </p>
<p>
        Parsing result object can be implicitly converted to <code class="computeroutput"><span class="keyword">bool</span></code>;
        if you do not want to handle parsing errors thoroughly, you can just check
        the return value of load functions as if it was a <code class="computeroutput"><span class="keyword">bool</span></code>:
        <code class="computeroutput"><span class="keyword">if</span> <span class="special">(</span><span class="identifier">doc</span><span class="special">.</span><span class="identifier">load_file</span><span class="special">(</span><span class="string">"file.xml"</span><span class="special">))</span> <span class="special">{</span> <span class="special">...</span>
        <span class="special">}</span> <span class="keyword">else</span> <span class="special">{</span> <span class="special">...</span> <span class="special">}</span></code>.
        Otherwise you can use the <code class="computeroutput"><span class="identifier">status</span></code>
        member to get parsing status, or the <code class="computeroutput"><span class="identifier">description</span><span class="special">()</span></code> member function to get the status in a
        string form.
      </p>
<p>
        This is an example of handling loading errors (<a href="samples/load_error_handling.cpp" target="_top">samples/load_error_handling.cpp</a>):
      </p>
<p>
        
</p>
<pre class="programlisting"><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_document</span> <span class="identifier">doc</span><span class="special">;</span>
<span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_parse_result</span> <span class="identifier">result</span> <span class="special">=</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">load</span><span class="special">(</span><span class="identifier">source</span><span class="special">);</span>

<span class="keyword">if</span> <span class="special">(</span><span class="identifier">result</span><span class="special">)</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"XML ["</span> <span class="special">&lt;&lt;</span> <span class="identifier">source</span> <span class="special">&lt;&lt;</span> <span class="string">"] parsed without errors, attr value: ["</span> <span class="special">&lt;&lt;</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">child</span><span class="special">(</span><span class="string">"node"</span><span class="special">).</span><span class="identifier">attribute</span><span class="special">(</span><span class="string">"attr"</span><span class="special">).</span><span class="identifier">value</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="string">"]\n\n"</span><span class="special">;</span>
<span class="keyword">else</span>
<span class="special">{</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"XML ["</span> <span class="special">&lt;&lt;</span> <span class="identifier">source</span> <span class="special">&lt;&lt;</span> <span class="string">"] parsed with errors, attr value: ["</span> <span class="special">&lt;&lt;</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">child</span><span class="special">(</span><span class="string">"node"</span><span class="special">).</span><span class="identifier">attribute</span><span class="special">(</span><span class="string">"attr"</span><span class="special">).</span><span class="identifier">value</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="string">"]\n"</span><span class="special">;</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"Error description: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">result</span><span class="special">.</span><span class="identifier">description</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="string">"\n"</span><span class="special">;</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"Error offset: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">result</span><span class="special">.</span><span class="identifier">offset</span> <span class="special">&lt;&lt;</span> <span class="string">" (error at [..."</span> <span class="special">&lt;&lt;</span> <span class="special">(</span><span class="identifier">source</span> <span class="special">+</span> <span class="identifier">result</span><span class="special">.</span><span class="identifier">offset</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="string">"]\n\n"</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
      </p>
<p>
        Sometimes XML data should be loaded from some other source than file, i.e.
        HTTP URL; also you may want to load XML data from file using non-standard
        functions, i.e. to use your virtual file system facilities or to load XML
        from gzip-compressed files. These scenarios either require loading document
        from memory, in which case you should prepare a contiguous memory block with
        all XML data and to pass it to one of buffer loading functions, or loading
        document from C++ IOstream, in which case you should provide an object which
        implements <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">istream</span></code> or <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">wistream</span></code>
        interface.
      </p>
<p>
        There are different functions for loading document from memory; they treat
        the passed buffer as either an immutable one (<code class="computeroutput"><span class="identifier">load_buffer</span></code>),
        a mutable buffer which is owned by the caller (<code class="computeroutput"><span class="identifier">load_buffer_inplace</span></code>),
        or a mutable buffer which ownership belongs to pugixml (<code class="computeroutput"><span class="identifier">load_buffer_inplace_own</span></code>).
        There is also a simple helper function, <code class="computeroutput"><span class="identifier">xml_document</span><span class="special">::</span><span class="identifier">load</span></code>,
        for cases when you want to load the XML document from null-terminated character
        string.
      </p>
<p>
        This is an example of loading XML document from memory using one of these
        functions (<a href="samples/load_memory.cpp" target="_top">samples/load_memory.cpp</a>);
        read the sample code for more examples:
      </p>
<p>
        
</p>
<pre class="programlisting"><span class="keyword">const</span> <span class="keyword">char</span> <span class="identifier">source</span><span class="special">[]</span> <span class="special">=</span> <span class="string">"&lt;mesh name='sphere'&gt;&lt;bounds&gt;0 0 1 1&lt;/bounds&gt;&lt;/mesh&gt;"</span><span class="special">;</span>
<span class="identifier">size_t</span> <span class="identifier">size</span> <span class="special">=</span> <span class="keyword">sizeof</span><span class="special">(</span><span class="identifier">source</span><span class="special">);</span>
</pre>
<p>
      </p>
<p>
        
</p>
<pre class="programlisting"><span class="comment">// You can use load_buffer_inplace to load document from mutable memory block; the block's lifetime must exceed that of document
</span><span class="keyword">char</span><span class="special">*</span> <span class="identifier">buffer</span> <span class="special">=</span> <span class="keyword">new</span> <span class="keyword">char</span><span class="special">[</span><span class="identifier">size</span><span class="special">];</span>
<span class="identifier">memcpy</span><span class="special">(</span><span class="identifier">buffer</span><span class="special">,</span> <span class="identifier">source</span><span class="special">,</span> <span class="identifier">size</span><span class="special">);</span>

<span class="comment">// The block can be allocated by any method; the block is modified during parsing
</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_parse_result</span> <span class="identifier">result</span> <span class="special">=</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">load_buffer_inplace</span><span class="special">(</span><span class="identifier">buffer</span><span class="special">,</span> <span class="identifier">size</span><span class="special">);</span>

<span class="comment">// You have to destroy the block yourself after the document is no longer used
</span><span class="keyword">delete</span><span class="special">[]</span> <span class="identifier">buffer</span><span class="special">;</span>
</pre>
<p>
      </p>
<p>
        This is a simple example of loading XML document from file using streams
        (<a href="samples/load_stream.cpp" target="_top">samples/load_stream.cpp</a>); read
        the sample code for more complex examples involving wide streams and locales:
      </p>
<p>
        
</p>
<pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">ifstream</span> <span class="identifier">stream</span><span class="special">(</span><span class="string">"weekly-utf-8.xml"</span><span class="special">);</span>
<span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_parse_result</span> <span class="identifier">result</span> <span class="special">=</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">load</span><span class="special">(</span><span class="identifier">stream</span><span class="special">);</span>
</pre>
<p>
      </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="quickstart.main.access"></a><a class="link" href="quickstart.html#quickstart.main.access" title="Accessing document data"> Accessing document data</a>
</h3></div></div></div>
<p>
        pugixml features an extensive interface for getting various types of data
        from the document and for traversing the document. You can use various accessors
        to get node/attribute data, you can traverse the child node/attribute lists
        via accessors or iterators, you can do depth-first traversals with <code class="computeroutput"><span class="identifier">xml_tree_walker</span></code> objects, and you can use
        XPath for complex data-driven queries.
      </p>
<p>
        You can get node or attribute name via <code class="computeroutput"><span class="identifier">name</span><span class="special">()</span></code> accessor, and value via <code class="computeroutput"><span class="identifier">value</span><span class="special">()</span></code> accessor. Note that both functions never
        return null pointers - they either return a string with the relevant content,
        or an empty string if name/value is absent or if the handle is null. Also
        there are two notable things for reading values:
      </p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
            It is common to store data as text contents of some node - i.e. <code class="computeroutput"><span class="special">&lt;</span><span class="identifier">node</span><span class="special">&gt;&lt;</span><span class="identifier">description</span><span class="special">&gt;</span><span class="identifier">This</span>
            <span class="identifier">is</span> <span class="identifier">a</span>
            <span class="identifier">node</span><span class="special">&lt;/</span><span class="identifier">description</span><span class="special">&gt;&lt;/</span><span class="identifier">node</span><span class="special">&gt;</span></code>.
            In this case, <code class="computeroutput"><span class="special">&lt;</span><span class="identifier">description</span><span class="special">&gt;</span></code> node does not have a value, but instead
            has a child of type <code class="computeroutput"><span class="identifier">node_pcdata</span></code>
            with value <code class="computeroutput"><span class="string">"This is a node"</span></code>.
            pugixml provides <code class="computeroutput"><span class="identifier">child_value</span><span class="special">()</span></code> helper functions to parse such data.
          </li>
<li class="listitem">
            In many cases attribute values have types that are not strings - i.e.
            an attribute may always contain values that should be treated as integers,
            despite the fact that they are represented as strings in XML. pugixml
            provides several accessors that convert attribute value to some other
            type.
          </li>
</ul></div>
<p>
        This is an example of using these functions (<a href="samples/traverse_base.cpp" target="_top">samples/traverse_base.cpp</a>):
      </p>
<p>
        
</p>
<pre class="programlisting"><span class="keyword">for</span> <span class="special">(</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">tool</span> <span class="special">=</span> <span class="identifier">tools</span><span class="special">.</span><span class="identifier">child</span><span class="special">(</span><span class="string">"Tool"</span><span class="special">);</span> <span class="identifier">tool</span><span class="special">;</span> <span class="identifier">tool</span> <span class="special">=</span> <span class="identifier">tool</span><span class="special">.</span><span class="identifier">next_sibling</span><span class="special">(</span><span class="string">"Tool"</span><span class="special">))</span>
<span class="special">{</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"Tool "</span> <span class="special">&lt;&lt;</span> <span class="identifier">tool</span><span class="special">.</span><span class="identifier">attribute</span><span class="special">(</span><span class="string">"Filename"</span><span class="special">).</span><span class="identifier">value</span><span class="special">();</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">": AllowRemote "</span> <span class="special">&lt;&lt;</span> <span class="identifier">tool</span><span class="special">.</span><span class="identifier">attribute</span><span class="special">(</span><span class="string">"AllowRemote"</span><span class="special">).</span><span class="identifier">as_bool</span><span class="special">();</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">", Timeout "</span> <span class="special">&lt;&lt;</span> <span class="identifier">tool</span><span class="special">.</span><span class="identifier">attribute</span><span class="special">(</span><span class="string">"Timeout"</span><span class="special">).</span><span class="identifier">as_int</span><span class="special">();</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">", Description '"</span> <span class="special">&lt;&lt;</span> <span class="identifier">tool</span><span class="special">.</span><span class="identifier">child_value</span><span class="special">(</span><span class="string">"Description"</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="string">"'\n"</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
      </p>
<p>
        Since a lot of document traversal consists of finding the node/attribute
        with the correct name, there are special functions for that purpose. For
        example, <code class="computeroutput"><span class="identifier">child</span><span class="special">(</span><span class="string">"Tool"</span><span class="special">)</span></code>
        returns the first node which has the name <code class="computeroutput"><span class="string">"Tool"</span></code>,
        or null handle if there is no such node. This is an example of using such
        functions (<a href="samples/traverse_base.cpp" target="_top">samples/traverse_base.cpp</a>):
      </p>
<p>
        
</p>
<pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"Tool for *.dae generation: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">tools</span><span class="special">.</span><span class="identifier">find_child_by_attribute</span><span class="special">(</span><span class="string">"Tool"</span><span class="special">,</span> <span class="string">"OutputFileMasks"</span><span class="special">,</span> <span class="string">"*.dae"</span><span class="special">).</span><span class="identifier">attribute</span><span class="special">(</span><span class="string">"Filename"</span><span class="special">).</span><span class="identifier">value</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="string">"\n"</span><span class="special">;</span>

<span class="keyword">for</span> <span class="special">(</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">tool</span> <span class="special">=</span> <span class="identifier">tools</span><span class="special">.</span><span class="identifier">child</span><span class="special">(</span><span class="string">"Tool"</span><span class="special">);</span> <span class="identifier">tool</span><span class="special">;</span> <span class="identifier">tool</span> <span class="special">=</span> <span class="identifier">tool</span><span class="special">.</span><span class="identifier">next_sibling</span><span class="special">(</span><span class="string">"Tool"</span><span class="special">))</span>
<span class="special">{</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"Tool "</span> <span class="special">&lt;&lt;</span> <span class="identifier">tool</span><span class="special">.</span><span class="identifier">attribute</span><span class="special">(</span><span class="string">"Filename"</span><span class="special">).</span><span class="identifier">value</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="string">"\n"</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
      </p>
<p>
        Child node lists and attribute lists are simply double-linked lists; while
        you can use <code class="computeroutput"><span class="identifier">previous_sibling</span></code>/<code class="computeroutput"><span class="identifier">next_sibling</span></code> and other such functions for
        iteration, pugixml additionally provides node and attribute iterators, so
        that you can treat nodes as containers of other nodes or attributes. All
        iterators are bidirectional and support all usual iterator operations. The
        iterators are invalidated if the node/attribute objects they're pointing
        to are removed from the tree; adding nodes/attributes does not invalidate
        any iterators.
      </p>
<p>
        Here is an example of using iterators for document traversal (<a href="samples/traverse_iter.cpp" target="_top">samples/traverse_iter.cpp</a>):
      </p>
<p>
        
</p>
<pre class="programlisting"><span class="keyword">for</span> <span class="special">(</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node_iterator</span> <span class="identifier">it</span> <span class="special">=</span> <span class="identifier">tools</span><span class="special">.</span><span class="identifier">begin</span><span class="special">();</span> <span class="identifier">it</span> <span class="special">!=</span> <span class="identifier">tools</span><span class="special">.</span><span class="identifier">end</span><span class="special">();</span> <span class="special">++</span><span class="identifier">it</span><span class="special">)</span>
<span class="special">{</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"Tool:"</span><span class="special">;</span>

    <span class="keyword">for</span> <span class="special">(</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_attribute_iterator</span> <span class="identifier">ait</span> <span class="special">=</span> <span class="identifier">it</span><span class="special">-&gt;</span><span class="identifier">attributes_begin</span><span class="special">();</span> <span class="identifier">ait</span> <span class="special">!=</span> <span class="identifier">it</span><span class="special">-&gt;</span><span class="identifier">attributes_end</span><span class="special">();</span> <span class="special">++</span><span class="identifier">ait</span><span class="special">)</span>
    <span class="special">{</span>
        <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">" "</span> <span class="special">&lt;&lt;</span> <span class="identifier">ait</span><span class="special">-&gt;</span><span class="identifier">name</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="string">"="</span> <span class="special">&lt;&lt;</span> <span class="identifier">ait</span><span class="special">-&gt;</span><span class="identifier">value</span><span class="special">();</span>
    <span class="special">}</span>

    <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
      </p>
<p>
        The methods described above allow traversal of immediate children of some
        node; if you want to do a deep tree traversal, you'll have to do it via a
        recursive function or some equivalent method. However, pugixml provides a
        helper for depth-first traversal of a subtree. In order to use it, you have
        to implement <code class="computeroutput"><span class="identifier">xml_tree_walker</span></code>
        interface and to call <code class="computeroutput"><span class="identifier">traverse</span></code>
        function.
      </p>
<p>
        This is an example of traversing tree hierarchy with xml_tree_walker (<a href="samples/traverse_walker.cpp" target="_top">samples/traverse_walker.cpp</a>):
      </p>
<p>
        
</p>
<pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">simple_walker</span><span class="special">:</span> <span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_tree_walker</span>
<span class="special">{</span>
    <span class="keyword">virtual</span> <span class="keyword">bool</span> <span class="identifier">for_each</span><span class="special">(</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span><span class="special">&amp;</span> <span class="identifier">node</span><span class="special">)</span>
    <span class="special">{</span>
        <span class="keyword">for</span> <span class="special">(</span><span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> <span class="identifier">i</span> <span class="special">&lt;</span> <span class="identifier">depth</span><span class="special">();</span> <span class="special">++</span><span class="identifier">i</span><span class="special">)</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"  "</span><span class="special">;</span> <span class="comment">// indentation
</span>
        <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">node_types</span><span class="special">[</span><span class="identifier">node</span><span class="special">.</span><span class="identifier">type</span><span class="special">()]</span> <span class="special">&lt;&lt;</span> <span class="string">": name='"</span> <span class="special">&lt;&lt;</span> <span class="identifier">node</span><span class="special">.</span><span class="identifier">name</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="string">"', value='"</span> <span class="special">&lt;&lt;</span> <span class="identifier">node</span><span class="special">.</span><span class="identifier">value</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="string">"'\n"</span><span class="special">;</span>

        <span class="keyword">return</span> <span class="keyword">true</span><span class="special">;</span> <span class="comment">// continue traversal
</span>    <span class="special">}</span>
<span class="special">};</span>
</pre>
<p>
      </p>
<p>
        
</p>
<pre class="programlisting"><span class="identifier">simple_walker</span> <span class="identifier">walker</span><span class="special">;</span>
<span class="identifier">doc</span><span class="special">.</span><span class="identifier">traverse</span><span class="special">(</span><span class="identifier">walker</span><span class="special">);</span>
</pre>
<p>
      </p>
<p>
        Finally, for complex queries often a higher-level DSL is needed. pugixml
        provides an implementation of XPath 1.0 language for such queries. The complete
        description of XPath usage can be found in the manual, but here are some
        examples:
      </p>
<p>
        
</p>
<pre class="programlisting"><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xpath_node_set</span> <span class="identifier">tools</span> <span class="special">=</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">select_nodes</span><span class="special">(</span><span class="string">"/Profile/Tools/Tool[@AllowRemote='true' and @DeriveCaptionFrom='lastparam']"</span><span class="special">);</span>

<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"Tools:"</span><span class="special">;</span>

<span class="keyword">for</span> <span class="special">(</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xpath_node_set</span><span class="special">::</span><span class="identifier">const_iterator</span> <span class="identifier">it</span> <span class="special">=</span> <span class="identifier">tools</span><span class="special">.</span><span class="identifier">begin</span><span class="special">();</span> <span class="identifier">it</span> <span class="special">!=</span> <span class="identifier">tools</span><span class="special">.</span><span class="identifier">end</span><span class="special">();</span> <span class="special">++</span><span class="identifier">it</span><span class="special">)</span>
<span class="special">{</span>
    <span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xpath_node</span> <span class="identifier">node</span> <span class="special">=</span> <span class="special">*</span><span class="identifier">it</span><span class="special">;</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">" "</span> <span class="special">&lt;&lt;</span> <span class="identifier">node</span><span class="special">.</span><span class="identifier">node</span><span class="special">().</span><span class="identifier">attribute</span><span class="special">(</span><span class="string">"Filename"</span><span class="special">).</span><span class="identifier">value</span><span class="special">();</span>
<span class="special">}</span>

<span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xpath_node</span> <span class="identifier">build_tool</span> <span class="special">=</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">select_single_node</span><span class="special">(</span><span class="string">"//Tool[contains(Description, 'build system')]"</span><span class="special">);</span>

<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"\nBuild tool: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">build_tool</span><span class="special">.</span><span class="identifier">node</span><span class="special">().</span><span class="identifier">attribute</span><span class="special">(</span><span class="string">"Filename"</span><span class="special">).</span><span class="identifier">value</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="string">"\n"</span><span class="special">;</span>
</pre>
<p>
      </p>
<div class="caution"><table border="0" summary="Caution">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Caution]" src="images/caution.png"></td>
<th align="left">Caution</th>
</tr>
<tr><td align="left" valign="top"><p>
          XPath functions throw <code class="computeroutput"><span class="identifier">xpath_exception</span></code>
          objects on error; the sample above does not catch these exceptions.
        </p></td></tr>
</table></div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="quickstart.main.modify"></a><a class="link" href="quickstart.html#quickstart.main.modify" title="Modifying document data"> Modifying document data</a>
</h3></div></div></div>
<p>
        The document in pugixml is fully mutable: you can completely change the document
        structure and modify the data of nodes/attributes. All functions take care
        of memory management and structural integrity themselves, so they always
        result in structurally valid tree - however, it is possible to create an
        invalid XML tree (for example, by adding two attributes with the same name
        or by setting attribute/node name to empty/invalid string). Tree modification
        is optimized for performance and for memory consumption, so if you have enough
        memory you can create documents from scratch with pugixml and later save
        them to file/stream instead of relying on error-prone manual text writing
        and without too much overhead.
      </p>
<p>
        All member functions that change node/attribute data or structure are non-constant
        and thus can not be called on constant handles. However, you can easily convert
        constant handle to non-constant one by simple assignment: <code class="computeroutput"><span class="keyword">void</span>
        <span class="identifier">foo</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span><span class="special">&amp;</span> <span class="identifier">n</span><span class="special">)</span> <span class="special">{</span> <span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">nc</span> <span class="special">=</span> <span class="identifier">n</span><span class="special">;</span> <span class="special">}</span></code>, so const-correctness
        here mainly provides additional documentation.
      </p>
<p>
        As discussed before, nodes can have name and value, both of which are strings.
        Depending on node type, name or value may be absent. You can use <code class="computeroutput"><span class="identifier">set_name</span></code> and <code class="computeroutput"><span class="identifier">set_value</span></code>
        member functions to set them. Similar functions are available for attributes;
        however, the <code class="computeroutput"><span class="identifier">set_value</span></code> function
        is overloaded for some other types except strings, like floating-point numbers.
        Also, attribute value can be set using an assignment operator. This is an
        example of setting node/attribute name and value (<a href="samples/modify_base.cpp" target="_top">samples/modify_base.cpp</a>):
      </p>
<p>
        
</p>
<pre class="programlisting"><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">node</span> <span class="special">=</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">child</span><span class="special">(</span><span class="string">"node"</span><span class="special">);</span>

<span class="comment">// change node name
</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">node</span><span class="special">.</span><span class="identifier">set_name</span><span class="special">(</span><span class="string">"notnode"</span><span class="special">);</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">", new node name: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">node</span><span class="special">.</span><span class="identifier">name</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>

<span class="comment">// change comment text
</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">last_child</span><span class="special">().</span><span class="identifier">set_value</span><span class="special">(</span><span class="string">"useless comment"</span><span class="special">);</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">", new comment text: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">last_child</span><span class="special">().</span><span class="identifier">value</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>

<span class="comment">// we can't change value of the element or name of the comment
</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">node</span><span class="special">.</span><span class="identifier">set_value</span><span class="special">(</span><span class="string">"1"</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="string">", "</span> <span class="special">&lt;&lt;</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">last_child</span><span class="special">().</span><span class="identifier">set_name</span><span class="special">(</span><span class="string">"2"</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
</pre>
<p>
      </p>
<p>
        
</p>
<pre class="programlisting"><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_attribute</span> <span class="identifier">attr</span> <span class="special">=</span> <span class="identifier">node</span><span class="special">.</span><span class="identifier">attribute</span><span class="special">(</span><span class="string">"id"</span><span class="special">);</span>

<span class="comment">// change attribute name/value
</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">attr</span><span class="special">.</span><span class="identifier">set_name</span><span class="special">(</span><span class="string">"key"</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="string">", "</span> <span class="special">&lt;&lt;</span> <span class="identifier">attr</span><span class="special">.</span><span class="identifier">set_value</span><span class="special">(</span><span class="string">"345"</span><span class="special">);</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">", new attribute: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">attr</span><span class="special">.</span><span class="identifier">name</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="string">"="</span> <span class="special">&lt;&lt;</span> <span class="identifier">attr</span><span class="special">.</span><span class="identifier">value</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>

<span class="comment">// we can use numbers or booleans
</span><span class="identifier">attr</span><span class="special">.</span><span class="identifier">set_value</span><span class="special">(</span><span class="number">1.234</span><span class="special">);</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"new attribute value: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">attr</span><span class="special">.</span><span class="identifier">value</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>

<span class="comment">// we can also use assignment operators for more concise code
</span><span class="identifier">attr</span> <span class="special">=</span> <span class="keyword">true</span><span class="special">;</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"final attribute value: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">attr</span><span class="special">.</span><span class="identifier">value</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
</pre>
<p>
      </p>
<p>
        Nodes and attributes do not exist without a document tree, so you can't create
        them without adding them to some document. A node or attribute can be created
        at the end of node/attribute list or before/after some other node. All insertion
        functions return the handle to newly created object on success, and null
        handle on failure. Even if the operation fails (for example, if you're trying
        to add a child node to PCDATA node), the document remains in consistent state,
        but the requested node/attribute is not added.
      </p>
<div class="caution"><table border="0" summary="Caution">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Caution]" src="images/caution.png"></td>
<th align="left">Caution</th>
</tr>
<tr><td align="left" valign="top"><p>
          attribute() and child() functions do not add attributes or nodes to the
          tree, so code like <code class="computeroutput"><span class="identifier">node</span><span class="special">.</span><span class="identifier">attribute</span><span class="special">(</span><span class="string">"id"</span><span class="special">)</span> <span class="special">=</span> <span class="number">123</span><span class="special">;</span></code> will not do anything if <code class="computeroutput"><span class="identifier">node</span></code> does not have an attribute with
          name <code class="computeroutput"><span class="string">"id"</span></code>. Make sure
          you're operating with existing attributes/nodes by adding them if necessary.
        </p></td></tr>
</table></div>
<p>
        This is an example of adding new attributes/nodes to the document (<a href="samples/modify_add.cpp" target="_top">samples/modify_add.cpp</a>):
      </p>
<p>
        
</p>
<pre class="programlisting"><span class="comment">// add node with some name
</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">node</span> <span class="special">=</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">append_child</span><span class="special">(</span><span class="string">"node"</span><span class="special">);</span>

<span class="comment">// add description node with text child
</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">descr</span> <span class="special">=</span> <span class="identifier">node</span><span class="special">.</span><span class="identifier">append_child</span><span class="special">(</span><span class="string">"description"</span><span class="special">);</span>
<span class="identifier">descr</span><span class="special">.</span><span class="identifier">append_child</span><span class="special">(</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">node_pcdata</span><span class="special">).</span><span class="identifier">set_value</span><span class="special">(</span><span class="string">"Simple node"</span><span class="special">);</span>

<span class="comment">// add param node before the description
</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">param</span> <span class="special">=</span> <span class="identifier">node</span><span class="special">.</span><span class="identifier">insert_child_before</span><span class="special">(</span><span class="string">"param"</span><span class="special">,</span> <span class="identifier">descr</span><span class="special">);</span>

<span class="comment">// add attributes to param node
</span><span class="identifier">param</span><span class="special">.</span><span class="identifier">append_attribute</span><span class="special">(</span><span class="string">"name"</span><span class="special">)</span> <span class="special">=</span> <span class="string">"version"</span><span class="special">;</span>
<span class="identifier">param</span><span class="special">.</span><span class="identifier">append_attribute</span><span class="special">(</span><span class="string">"value"</span><span class="special">)</span> <span class="special">=</span> <span class="number">1.1</span><span class="special">;</span>
<span class="identifier">param</span><span class="special">.</span><span class="identifier">insert_attribute_after</span><span class="special">(</span><span class="string">"type"</span><span class="special">,</span> <span class="identifier">param</span><span class="special">.</span><span class="identifier">attribute</span><span class="special">(</span><span class="string">"name"</span><span class="special">))</span> <span class="special">=</span> <span class="string">"float"</span><span class="special">;</span>
</pre>
<p>
      </p>
<p>
        If you do not want your document to contain some node or attribute, you can
        remove it with <code class="computeroutput"><span class="identifier">remove_attribute</span></code>
        and <code class="computeroutput"><span class="identifier">remove_child</span></code> functions.
        Removing the attribute or node invalidates all handles to the same underlying
        object, and also invalidates all iterators pointing to the same object. Removing
        node also invalidates all past-the-end iterators to its attribute or child
        node list. Be careful to ensure that all such handles and iterators either
        do not exist or are not used after the attribute/node is removed.
      </p>
<p>
        This is an example of removing attributes/nodes from the document (<a href="samples/modify_remove.cpp" target="_top">samples/modify_remove.cpp</a>):
      </p>
<p>
        
</p>
<pre class="programlisting"><span class="comment">// remove description node with the whole subtree
</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">node</span> <span class="special">=</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">child</span><span class="special">(</span><span class="string">"node"</span><span class="special">);</span>
<span class="identifier">node</span><span class="special">.</span><span class="identifier">remove_child</span><span class="special">(</span><span class="string">"description"</span><span class="special">);</span>

<span class="comment">// remove id attribute
</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">param</span> <span class="special">=</span> <span class="identifier">node</span><span class="special">.</span><span class="identifier">child</span><span class="special">(</span><span class="string">"param"</span><span class="special">);</span>
<span class="identifier">param</span><span class="special">.</span><span class="identifier">remove_attribute</span><span class="special">(</span><span class="string">"value"</span><span class="special">);</span>

<span class="comment">// we can also remove nodes/attributes by handles
</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_attribute</span> <span class="identifier">id</span> <span class="special">=</span> <span class="identifier">param</span><span class="special">.</span><span class="identifier">attribute</span><span class="special">(</span><span class="string">"name"</span><span class="special">);</span>
<span class="identifier">param</span><span class="special">.</span><span class="identifier">remove_attribute</span><span class="special">(</span><span class="identifier">id</span><span class="special">);</span>
</pre>
<p>
      </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="quickstart.main.saving"></a><a class="link" href="quickstart.html#quickstart.main.saving" title="Saving document"> Saving document</a>
</h3></div></div></div>
<p>
        Often after creating a new document or loading the existing one and processing
        it, it is necessary to save the result back to file. Also it is occasionally
        useful to output the whole document or a subtree to some stream; use cases
        include debug printing, serialization via network or other text-oriented
        medium, etc. pugixml provides several functions to output any subtree of
        the document to a file, stream or another generic transport interface; these
        functions allow to customize the output format, and also perform necessary
        encoding conversions.
      </p>
<p>
        Before writing to the destination the node/attribute data is properly formatted
        according to the node type; all special XML symbols, such as &lt; and &amp;,
        are properly escaped. In order to guard against forgotten node/attribute
        names, empty node/attribute names are printed as <code class="computeroutput"><span class="string">":anonymous"</span></code>.
        For well-formed output, make sure all node and attribute names are set to
        meaningful values.
      </p>
<p>
        If you want to save the whole document to a file, you can use the <code class="computeroutput"><span class="identifier">save_file</span></code> function, which returns <code class="computeroutput"><span class="keyword">true</span></code> on success. This is a simple example
        of saving XML document to file (<a href="samples/save_file.cpp" target="_top">samples/save_file.cpp</a>):
      </p>
<p>
        
</p>
<pre class="programlisting"><span class="comment">// save document to file
</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"Saving result: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">save_file</span><span class="special">(</span><span class="string">"save_file_output.xml"</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
</pre>
<p>
      </p>
<p>
        To enhance interoperability pugixml provides functions for saving document
        to any object which implements C++ <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">ostream</span></code>
        interface. This allows you to save documents to any standard C++ stream (i.e.
        file stream) or any third-party compliant implementation (i.e. Boost Iostreams).
        Most notably, this allows for easy debug output, since you can use <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span></code>
        stream as saving target. There are two functions, one works with narrow character
        streams, another handles wide character ones.
      </p>
<p>
        This is a simple example of saving XML document to standard output (<a href="samples/save_stream.cpp" target="_top">samples/save_stream.cpp</a>):
      </p>
<p>
        
</p>
<pre class="programlisting"><span class="comment">// save document to standard output
</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"Document:\n"</span><span class="special">;</span>
<span class="identifier">doc</span><span class="special">.</span><span class="identifier">save</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span><span class="special">);</span>
</pre>
<p>
      </p>
<p>
        All of the above saving functions are implemented in terms of writer interface.
        This is a simple interface with a single function, which is called several
        times during output process with chunks of document data as input. In order
        to output the document via some custom transport, for example sockets, you
        should create an object which implements <code class="computeroutput"><span class="identifier">xml_writer_file</span></code>
        interface and pass it to <code class="computeroutput"><span class="identifier">xml_document</span><span class="special">::</span><span class="identifier">save</span></code>
        function.
      </p>
<p>
        This is a simple example of custom writer for saving document data to STL
        string (<a href="samples/save_custom_writer.cpp" target="_top">samples/save_custom_writer.cpp</a>);
        read the sample code for more complex examples:
      </p>
<p>
        
</p>
<pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">xml_string_writer</span><span class="special">:</span> <span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_writer</span>
<span class="special">{</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">result</span><span class="special">;</span>

    <span class="keyword">virtual</span> <span class="keyword">void</span> <span class="identifier">write</span><span class="special">(</span><span class="keyword">const</span> <span class="keyword">void</span><span class="special">*</span> <span class="identifier">data</span><span class="special">,</span> <span class="identifier">size_t</span> <span class="identifier">size</span><span class="special">)</span>
    <span class="special">{</span>
        <span class="identifier">result</span> <span class="special">+=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">(</span><span class="keyword">static_cast</span><span class="special">&lt;</span><span class="keyword">const</span> <span class="keyword">char</span><span class="special">*&gt;(</span><span class="identifier">data</span><span class="special">),</span> <span class="identifier">size</span><span class="special">);</span>
    <span class="special">}</span>
<span class="special">};</span>
</pre>
<p>
      </p>
<p>
        While the previously described functions save the whole document to the destination,
        it is easy to save a single subtree. Instead of calling <code class="computeroutput"><span class="identifier">xml_document</span><span class="special">::</span><span class="identifier">save</span></code>,
        just call <code class="computeroutput"><span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">print</span></code> function on the target node. You
        can save node contents to C++ IOstream object or custom writer in this way.
        Saving a subtree slightly differs from saving the whole document; <a href="manual/saving.html#manual.saving.subtree" target="_top">read the manual</a> for
        more information.
      </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="quickstart.main.feedback"></a><a class="link" href="quickstart.html#quickstart.main.feedback" title="Feedback"> Feedback</a>
</h3></div></div></div>
<p>
        If you believe you've found a bug in pugixml, please file an issue via <a href="http://code.google.com/p/pugixml/issues/entry" target="_top">issue submission form</a>.
        Be sure to include the relevant information so that the bug can be reproduced:
        the version of pugixml, compiler version and target architecture, the code
        that uses pugixml and exhibits the bug, etc. Feature requests and contributions
        can be filed as issues, too.
      </p>
<a name="email"></a><p>
        If filing an issue is not possible due to privacy or other concerns, you
        can contact pugixml author by e-mail directly: <a href="mailto:arseny.kapoulkine@gmail.com" target="_top">arseny.kapoulkine@gmail.com</a>.
      </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="quickstart.main.license"></a><a class="link" href="quickstart.html#quickstart.main.license" title="License"> License</a>
</h3></div></div></div>
<p>
        The pugixml library is distributed under the MIT license:
      </p>
<div class="blockquote"><blockquote class="blockquote">
<p>
          Copyright (c) 2006-2010 Arseny Kapoulkine
        </p>
<p>
          Permission is hereby granted, free of charge, to any person obtaining a
          copy of this software and associated documentation files (the "Software"),
          to deal in the Software without restriction, including without limitation
          the rights to use, copy, modify, merge, publish, distribute, sublicense,
          and/or sell copies of the Software, and to permit persons to whom the Software
          is furnished to do so, subject to the following conditions:
        </p>
<p>
          The above copyright notice and this permission notice shall be included
          in all copies or substantial portions of the Software.
        </p>
<p>
          THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
          EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
          FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
          THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
          LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
          FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
          IN THE SOFTWARE.
        </p>
</blockquote></div>
<p>
        This means that you can freely use pugixml in your applications, both open-source
        and proprietary. If you use pugixml in a product, it is sufficient to add
        an acknowledgment like this to the product distribution:
      </p>
<div class="blockquote"><blockquote class="blockquote"><p>
          This software is based on pugixml library (http://pugixml.org).<br>
pugixml
          is Copyright (C) 2006-2010 Arseny Kapoulkine.
        </p></blockquote></div>
</div>
</div>
<div class="footnotes">
<br><hr width="100" align="left">
<div class="footnote"><p><sup>[<a name="ftn.trademarks" href="#trademarks" class="para">1</a>] </sup>All trademarks used are properties of their respective owners.</p></div>
</div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"><p><small>Last revised: October 31, 2010 at 07:44:52 GMT</small></p></td>
<td align="right"><div class="copyright-footer"></div></td>
</tr></table>
</body>
</html>
